This is an application for a competing renewal of the five-year cooperative agreement with the National Institute on Aging, to design and collect data for a Health and Retirement Study (HRS). In the first five-year period, we designed the baseline survey for the birth cohorts of 1931-1941, screened 70,000 households to identify the eligible birth cohorts and their spouses, collected baseline data on some 12.6 thousand persons in some 7,700 households, collected data for the first follow-up survey (Wave 2), and collected employer data on health insurance and pension plans. This application covers years 6-10 of the HRS; it includes the design and data collection of two additional follow-up surveys for the original cohort (Waves 3 and 4), the introduction of a new cohort (those born 1942-1947 and their spouses), and an employer survey of health insurance and pension plans for the new cohort. In the design of Wave 2, now in the field, we concentrate on updating various state conditions that are inherently discrete (marital status, housing status, family composition, disease conditions, disability status), remeasuring respondent characteristics that are inherently continuous (income flows, transfers, expenditures, net worth functional health, expectations and cognitive functioning), and reconstructing labor market status on a month-by-month basis over the interval between Waves 1 and 2. With these data, analysts can begin to assess the dynamics of retirement decisions. The design of Waves 3 and 4 is expected to follow closely on the design of Wave 2. The resulting dataset will permit analysts to estimate a variety of models designed to explain these crucial labor market outcomes, and to begin to understand the determinants of retirement and disability status in the environment of the 1990s. In addition, we propose to add a new cohort in 1998, covering the birth cohorts of 1942-1947. The introduction of new cohorts on a systematic basis is a critical part of the design for a study like HRS, and will enable analysts to understand the evolution of retirement decisions and the economic and health consequences of aging throughout the critical next few decades. Finally, we describe ways to improve the coordination between HRS and the related study of Asset and Health Dynamics Among the Oldest Old (AHEAD). The two studies should be tightly linked together in terms of content, since in the long-run HRS households would be expected to phase into the AHEAD age-range and be interviewed with the AHEAD survey instrument. While the two studies have a quite different analytical focus at present, content decisions and survey strategy need to be closely coordinated.